Electrostatic interactions play a minor role in the binding of ExoS to 14-3-3 proteins
2010 (English)In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 427, no 2, 217-224 p.Article in journal (Refereed) Published
14-3-3 proteins belong to a family of conserved molecules expressed in all eukaryotic cells that play an important role in a multitude of signalling pathways. 14-3-3 proteins bind either to phosphoserine/phosphothreonine residues or to sequence-specific non-phosphorylated motifs in more than 200 interaction partners [Pozuelo Rubio, Geraghty, Wong, Wood, Campbell, Morrice and Mackintosh (2004) Biochem. J. 379, 395-408]. These interactions result in cell-cycle regulation, apoptosis, stress responses, cell metabolism and malignant transformation. One example of a phosphorylation-independent interaction is the binding of 14-3-3 to ExoS (exoenzyme S), a bacterial ADP-ribosyltransferase toxin of Pseudomonas aeruginosa. In the present study, we have utilized additional biochemical and infection analyses to define further the structural basis of the interaction between ExoS and 14-3-3. An ExoS leucine-substitution mutant dramatically reduced the interaction potential with 14-3-3 suggesting that Leu422, Leu423, Leu426 and Leu428 of ExoS are important for its interaction with 14-3-3, its enzymatic activity and cytotoxicity. However, ExoS substitution mutants of residues that interact with 14-3-3 through an electrostatic interaction, such as Ser416, His418, Asp424 and Asp427, showed no reduction in their interaction potential with 14-3-3. These ExoS substitution mutants were also as aggressive as wild-type ExoS at inducing cell death and to modify endogenous ExoS target within the cell. In conclusion, electrostatic interaction between ExoS and 14-3-3 via polar residues (Ser416, His418, Asp424 and Asp427) appears to be of secondary importance. Thus the interaction between the 'roof' of the groove of 14-3-3 and ExoS relies more on hydrophobic interaction forces, which probably contributes to induce cell death after ExoS infection and activation.
Place, publisher, year, edition, pages
Portland Press, 2010. Vol. 427, no 2, 217-224 p.
ADP-ribosyltransferase, Akt/protein kinase B (PKB), exoenzyme S (ExoS), 14-3-3 protein, Pseudomonas aeruginosa, Ras
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:umu:diva-33086DOI: 10.1042/BJ20100043ISI: 000276867100004PubMedID: 20144150OAI: oai:DiVA.org:umu-33086DiVA: diva2:310040